1. Field of the Invention
This invention relates to a method for manufacturing a laminate product, as well as to laminate products which are obtained in accordance with this method, and to a device for realizing the method.
2. Related Art
In particular, the invention relates to a method for manufacturing a laminate product comprising at least a laminate layer, wherein, for forming the laminate layer, on the one hand, at least a decor sheet is formed by providing in a decor application process a decor in the form of a motif on a decor carrier and, on the other hand, subsequently providing the decor sheet with resin by means of a resin application process.
According to the invention, by a laminate product each product has to be understood which consists at least of a laminate layer, which as such comprises at least a decor sheet formed of a decor carrier upon which a decor in the form of a motif is applied and wherein this decor sheet is provided with an amount of resin, more particularly is soaked in resin and/or is impregnated with resin.
According to the invention, such “laminate product” thus can relate to said laminate layer as such, whether or not in hardened condition, as well as any other product comprising such laminate layer. By the last-mentioned other products, substantially products are intended which principally consist of a substrate covered with such laminate layer, whether or not combined with still other layers.
Herein, an important application range are laminate panels, in the first place laminate floor panels, however, in the second place also laminate panels for other purposes, such as for furniture, partition walls and the like. Of course, this may also relate to other products than panels, such as, for example, profiles, skirting boards and such, which comprise a covering of such laminate layer. Further, such products as such may also consist of a composed layer structure in which such laminate layer is incorporated, such as a so-called HPL (High Pressure Laminate) or a compact laminate, of which the laminate layer realized according to the invention then forms part.
It is known to realize a laminate product comprising at least a laminate layer by forming, in order to form the laminate layer, at least, on the one hand, a decor sheet by providing in a decor application process a decor in the form of a motif on a decor carrier and, on the other hand, by providing the decor sheet with resin by means of a resin application process.
Traditionally, the decor sheet is produced by printing a paper web with a decor. This printing is performed at a printer's, wherein this traditionally is performed by means of rotary printing. The printed decor determines the appearance of the decorative side of the final product. For example, for being applied in floor panels, the decor mostly represents an imitation of wood or stone, amongst which, in the latter case, natural stone as well as other kinds of stone, such as ceramics, concrete or the like may be understood by stone. In the case of an imitation of stone tiles, also cement grout lines or the like may be imitated in the decor.
The decor sheet is provided with an amount of resin by impregnating it with resin, either by immersing it in liquid resin, or by depositing resin thereon or by a combination thereof, after which the resin is dried. Traditionally, this is a step which is performed at the manufacturer of the actual laminate product, for example, at the manufacturer of the laminate floor panels, wherein the decor sheet, more particularly the printed paper web, is provided with resin in a continuous process and the drying is performed by guiding this paper width through one or more drying ovens.
Further, various techniques are known for attaching such laminate layer to a substrate. According to the much applied technique of so-called direct pressure laminate (DPL), the resin-impregnated decor sheet, or at least a portion thereof, is brought onto the substrate, possibly together with other layers, and the whole is consolidated by compressing it at a high temperature, which usually is performed in a heated press. Other layers, which herein may be pressed at the same time, are, for example, a so-called overlay and/or an underlying layer. The overlay mostly is formed from a resin-treated paper layer, in which wear-resistant particles incorporated, such as corundum or the like, and is provided over the decor in order to increase the wear resistance of the finally obtained floor panels. The paper layer of the overlay is of such nature that, after pressing and consolidating, it becomes almost completely transparent. According to a variant, it is also possible to work without an overlay and to apply wear-resistant particles in the resin present at the decor sheet instead. Said facultative underlying layer is a uniformly colored paper layer or the like, which can be provided between the substrate and the decor sheet and which, for example, prevents that color differences in the surface of the substrate would show through in the decorative side.
When pressing the whole, it is customary that also a balancing backing layer is provided at the underside of the substrate.
According to another known technique, namely, the technique of so-called high pressure laminate (HPL), the printed and resin-provided decor sheet first is consolidated with still other material sheets, preferably also impregnated paper webs or sheets, such that an as such relatively stable multi-layered laminate is obtained, which thereafter in its turn can be attached to a substrate, for example, by means of an adhesive.
According to another known technique, the printed and resin-provided decor sheet is pressed together with a plurality of other impregnated material layers, such that a self-supporting laminate structure is obtained, mostly in the form of a thin board, wherein the then obtained product is called “compact laminate”, which then mostly is applied without a substrate.
In the case of floor, furniture or wall panels, for said substrate mostly use is made of wood-based board material, mostly MDF (Medium Density Fiberboard) or HDF (High Density Fiberboard), however, other materials may also be applied.
A disadvantage with the known methods for forming a laminate product is that there is little interaction possible between, on the one hand, printing the decor sheet and, on the other hand, resin-treating the decor sheet; in other words, between the decor application process and the resin application process, in particular in that printing is performed at a printer's who supplies the resin-untreated decor sheet to the producers of the laminate, which last-mentioned producers then provide it with resin. This, however, results in that a relatively large buffer stock of printed decor sheet, more particularly, rolls of decor paper, will have to be stocked at the laminate producer's, in view of the fact that the latter must be sure of always having all motifs at hand. Another disadvantage is that when unexpectedly a decor with a certain motif should not be in stock, it takes a certain time until it can be supplied by the printer. Another disadvantage is that the laminate producer often has to store two stocks of decor sheets, more particularly decor paper, namely un-resinated decor sheet and resinated decor sheet.
Further, it is known that, when pressing the decor sheet impregnated with resin for hardening the resin, which mostly is performed when consolidating this decor sheet with the substrate or with other material sheets, a relief can be formed in the surface, more particularly in the form of impressions. Such impressions can be provided in accordance with the printed decor, which in English is called “registered embossed”. In the case of an imitation of wood, the impressions may imitate, for example, a natural relief of wood, in the form of impressions representing the pores and the like, in accordance with the printed wood motif. Also, joints between different planks represented by the decor and removed wood portions can be imitated by means of the impressions. In the case of an imitation of stone, also the natural relief of a stone species can be imitated in accordance with the printed decor, and/or impressions can be formed for representing lower-situated cement grout lines and the like.
Normally, the impressions are formed by making use of a press plate provided with a relief.
A difficulty when forming laminate with a relief intended to be in accordance with the decor consists in being able to realize such accordance in reality and with no or minor deviations over the entire surface of the decor sheet. In fact, the resin is provided on the decor sheet in liquid condition, as a result of which the wet decor sheet becomes sensitive to stretching and consequently is stretched during the resin application process.
It is known to take a certain stretching to be expected into account and thus to print the pattern on a somewhat smaller predetermined format than finally desired, in such a manner that the stretched motif obtained after resin application and drying then shows dimensions more or less corresponding to the desired dimensions. Due to the fact that the stretching in fact depends on a large number of parameters, a number of which also can be altered when processing one and the same decor carrier, it is often not sufficient to take a predetermined stretching into account, and often the relief pattern will not be in accordance with the printed pattern. Therefore, the decorative side of the obtained laminate products can show a deformed image.
A solution which can be applied in certain applications consists in designing two or three press plates having a similar relief pattern, however, the patterns of which mutually show a somewhat more stretched format, such that in function of the stretch pertaining to a certain production batch of decor carriers, the best-matching press plate can be applied. However, this technique is particularly expensive and provides only a limited solution. In fact, the technique does not allow taking alterations into account which can occur in a decor carrier itself, as, once a choice of press plate has been made, the entire decor carrier or batch of decor carriers is processed with the chosen press plate. Further, the chosen relief pattern mostly will not fully correspond to the printed pattern.
Further, it is known that in the length direction of the decor carrier, a small regulation of the stretching is possible by altering the tension force with which the decor carrier is fed through the resin application process. However, this regulation is limited and does not offer a solution for deformations in width direction.